Betaine remains an interesting additive with advanced applications in modern poultry feed formulations.
The major metabolic function of betaine is well-known, but it suffices to reiterate that betaine is a direct donor of methyl groups, a function similar to that of vitamin choline and amino acid methionine. In this respect, betaine can replace (or spare) methionine and choline. In addition, betaine is an osmotic regulator, one of the most important in physiology, acting in a way that keeps cells well-hydrated — a function that comes in handy during heat stress. Limited work has highlighted betaine as a lipotropic; it turns fat towards lean tissue synthesis, assuming there is sufficient protein in the feed.